This invention relates to pattern recognition systems in general and more particularly to plaid measuring systems.
Computer-controlled systems for automatically cutting the component pieces of clothing items are now in use in the apparel industry. In such systems the computer directs a cutting tool, such as the laser beam, reciprocating blade or fluid jet, for example, according to instructions prepared from a cutting plan. The advantages of such systems include reduced cutting cost, improved material utilization, and the elimination of the need for paper markers.
Pattern goods are of two types, i.e. stripes or plaids. Stripes are defined as goods which have a one-dimensional effect, generally confined to the direction along the bolt of cloth. In finished suits, for example, the stripes generally run from "head to toe" and stripe "matches" are usually limited to coat parts. The geometric uniformity of stripe pattern goods is usually quite good. On the other hand, plaid pattern goods are two-dimensional in nature with the stripe pattern along the length of the bolt and the line or bar pattern transverse to the length of the bolt. In finished suits, for example, the parts are matched in both stripe and bar dimensions. In plaid material, stripe uniformity is usually good but the bars are subject to manufacturing errors, and material (thread) variations, resulting in bar pattern distortion.
Heretofore, only plain or striped materials could be cut by computer-controlled systems and this is a costly limitation to manufacturers whose product line may be as much as 90% plaid goods. Manual control of plaid cutting requires a very high degree of operator skill as well as extra operational steps such as blocking and recutting.
In prior art systems for automatically cutting stripe goods, the bolt of material is placed in an automatic spreader located in front of a conveyor; an electronic stripe follower is "locked on" a selected center stripe and by closed loop "servo" control the material is placed on the moving conveyor belt in a straight line. Because only a few parts, such as a coat, have to be stripe matched, and since the stripe geometry is predictable, there is no need for pattern shifting and the "cut pattern" for the computer may be prepared beforehand.
Automated cutting of plaid materials presents a number of problems which result from the facts that:
Plaid suits must match in both the stripe and bar directions, i.e. two-dimensional matching; PA1 Plaid designs vary in geometry; and PA1 Plaid goods are distorted, the distortion is unpredictable and it varies as a function of handling, inspection, spreading of the material, etc.
If the plaid pattern repetition frequency, i.e. the separation between transverse bars, was constant and if the bars were not skewed, bowed or otherwise distorted, a computer could readily be programmed so that the individual parts are properly oriented on the plaid material to assure required match. Unfortunately, the repetition frequency of the transverse bars in plaid material is not stable nor are the bars straight, and a significant aspect of the subject invention deals with the resolution of these problems which heretofore have prohibited the automatic cutting of plaid material.